52 plate 406 glx hdi 110 cooling fan / a/c issues

[DAVEJERMYUK]

hi guys
i have a 52 plate 406 glx hdi 110
the air conditioning is not working, i,m a fridge engineer by trade and its not a gas problem as i checked the charge. there is no power to the compressor a mechanic friend has said it is the single cooling fan as i have 14v to the fan motor but its not running. ive just bought and fitted a new one at a cost of £200 and its still not working same thing 14v power through the relay to the motor and not running. there is 3 other little wires going to the fan motor any one know where or what they are doing
please help as its doing my head in

[DAVEJERMYUK]

furthur update just unplugged the temp sensor on the thermostat and came up with high temp alarm and the fan ran so i assume its not that, and also the fan works.
could it be that it is my pressurestat that is faulty and is not sending the signal to the fan motor
or
is it that the compressor should come on before the fan motor
cars are a guessing game to me

[Doggy]

Hi & welcome to the site.

The engine ecu controls the a/c compressor & rad fan - assuming everythings ok, it will energise the clutch & start the fan on slow speed.

a/c is disabled by low or high gas pressure, high engine temperature, low outside temp, (< 10 deg I think), among others.

Since you know what you're doing, try forcing the comp. clutch with a temporary supply / engine off & make sure you can hear the clutch engage. Then try the same briefly with engine running to prove it can produce cold air.

If you dont find any other cause, the prime suspect is the clutch relay, which lives inside the BSI, (Body Systems Interface - a complex electronic module resposible for controlling everything apart from the drivetrain, that lives above the passenger compartment fusebox).

May be worth a diagnostic session before attacking that....

Whereabouts are you (it helps to add your location as someone nearby may be able to help).

[Welly]

Hi,

Have you seen this? viewtopic.php?t=1452&start=0#p13555

[steve_earwig]

But if the compressor is getting 12 volts doesn't that rather imply the relay is ok?

Then again, perhaps it's h/r - not supplying enough current, and giving it a feed straight from the battery would prove if it's the compressor at fault.

[DAVEJERMYUK]

dogslife im in didcot, oxfordshire.
my mechanic had checked that the compressor works, so i think it is one of the sensors out of range as you mentioned as my car is fiited with a pressure sensor and not a stat as previously mentioned. so booked her into peugeot dealers for a diagnostics check £49.95 just to confirm my theory. 3rd time lucky eh.
bit of advice if its anything more than a regas either go to a car a/c company or the dealers as i,m thinking smaller but cheaper garages dont have the knowledge and would only call out an car a/c specialist anyway. will be gutted if its only been a sensor all along.

[Doggy]

If it's any help, I replaced the condenser on mine, had it (vacuum) leak tested, then regassed, but it still wouldn't go. Thinking i'd got a relay problem or similar, I 'forced' the clutch with a direct feed to prove it would give cold air, while I ws still at the garage, (which it did), then resolved to take it home & sort the electrics.

To my surprise, it worked OK from that point onwards!

My theory - the sensor is screwed into a non-return valve, so you can change it without losing the gas. When the system's empty, there's no residual pressure to 'tell' the sensor you have a good gas charge, so it effectively locks out on LP. When you 'force' the compressor on, you overcome the n/r valve & hey presto it works!